|  | 3.2 | Segmentation with Switching Architectures
| 3.2.1 |
Grouping geographically separate users into network-wide virtual topologies
LANs are increasingly being divided into workgroups connected via common backbones to form VLAN topologies. VLANs logically segment the physical LAN infrastructure into different subnets (or broadcast domains for Ethernet) so that broadcast frames are switched only between ports within the same VLAN. Initial VLAN implementations offered a port-mapping capability that established a broadcast domain between a default group of devices. Current network requirements demand VLAN functionality that covers the entire network. This approach to VLANs allows you to group geographically separate users in networkwide virtual topologies. VLAN configurations group users by logical association rather than physical location. The majority of the networks currently installed provide very limited logical segmentation. Users are commonly grouped based on connections to the shared hub and the router ports between the hubs. This topology provides segmentation only between the hubs, which are typically located on separate floors, and not between users connected to the same hub. This imposes physical constraints on the network and limits how users can be grouped. A few shared-hub architectures have some grouping capability, but they restrict how you configure logically defined workgroups.
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